Electrical transport through array of electrochemically etched silicon nanorods

Random arrays of oxide-passivated silicon nanorods have been obtained by natural oxidation of electrochemically etched porous silicon in air. The charge transport through these nanorods exhibits intriguing characteristics. The I–V characteristics are non-linear, asymmetric, hysteretic, and exhibit resistive switching. Three different charge transport mechanisms dominate in three different ranges of bias and temperature. At high bias, the Fowler–Nordheim tunneling through the oxide barrier is the dominant conduction mechanism. The Pool–Frenkel emission takes over at moderate bias, while at low bias, trap controlled space-charge-limited conduction is the governing mode of charge transport. The bias voltage for cross-over from one transport mechanism to another is sensitively dependent on temperature – the increase of temperature lowers the cross-over voltage. The observed phenomena can be explained in the framework of lateral transport through a disordered assembly of interconnected semiconducting nanorods. Such multiple transport mechanisms along with tunable cross-over from one mechanism to another simply by changing the bias or temperature, render these nanostructures amenable for a variety of applications. Additionally, the observed resistive switching makes them extremely promising candidates for low power-consuming resistive random access memory devices.